The present invention relates to a method for finishing a matted surface on a metal-made article for personal ornament or, more particularly, relates to a method for finishing a matted surface of an article for personal ornament made of titanium, zirconium or an alloy thereof to render the surface insusceptible to stain.
As is known, titanium, zirconium and alloys thereof have been used widely in space rockets and chemical plants by virtue of many excellent properties inherent thereto such as the outstandingly small specific gravity, high corrosion resistance, high specific strength, i.e. ratio of tensile strength to density, and the like. In recent years, however, the application fields of these metals and alloys are expanding also in the fields of metal-made articles for personal ornament such as watch cases, watch straps, bracelets, rings, brooches, pendants and the like. In respect of the surface finishing of such articles for personal ornament, major current of the recent preference of people is in the matted surface with dull or sandy appearance having extremely fine ruggedness, i.e. microscopically tiny protrusions and recesses, on the surface formed by honing or barrel finishing.
A problem in such a matted surface in general is the susceptibility of the surface to stain due to the deposition of perspiration or other excretions from the human skin as in the fingerprints as well as other dirts in the recesses or cavities on the finely rugged matted surface while such a dirty material can hardly be removed to completeness so that dirty spots are sometimes left on the surface to a great loss of the beautiful appearance. In this regard, it is proposed to provide a coating on the matted surface with, for example, a silicone fluid but such a coating material is readily removed away with a detergent or an alcoholic solvent so that no durable effect can of course be expected in such a means.